气候变化领域集成服务门户(CCPortal): Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria

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DOI	10.5194/tc-14-4063-2020
	Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria
	Hartl L.; Felbauer L.; Schwaizer G.; Fischer A.
发表日期	2020
ISSN	19940416
起始页码	4063
结束页码	4081
卷号	14 期号:11
英文摘要	As Alpine glaciers become snow-free in summer, more dark, bare ice is exposed, decreasing local albedo and increasing surface melting. To include this feedback mechanism in models of future deglaciation, it is important to understand the processes governing broadband and spectral albedo at a local scale. However, few in situ reflectance data have been measured in the ablation zones of mountain glaciers. As a contribution to this knowledge gap, we present spectral reflectance data (hemispherical-conical-reflectance factor) from 325 to 1075nm collected along several profile lines in the ablation zone of Jamtalferner, Austria. Measurements were timed to closely coincide with a Sentinel-2 and Landsat 8 overpass and are compared to the respective ground reflectance (bottom-of-atmosphere) products. The brightest spectra have a maximum reflectance of up to 0.7 and consist of clean, dry ice. In contrast, reflectance does not exceed 0.2 for dark spectra where liquid water and/or fine-grained debris are present. Spectra can roughly be grouped into dry ice, wet ice, and dirt or rocks, although gradations between these groups occur. Neither satellite captures the full range of in situ reflectance values. The difference between ground and satellite data is not uniform across satellite bands, between Landsat and Sentinel, and to some extent between ice surface types (underestimation of reflectance for bright surfaces, overestimation for dark surfaces). We highlight the need for further, systematic measurements of in situ spectral reflectance properties, their variability in time and space, and in-depth analysis of time-synchronous satellite data. © 2020 EDP Sciences. All rights reserved.
英文关键词	ablation; albedo; deglaciation; feedback mechanism; reflectance; satellite data; spatial variation; spectral reflectance; valley glacier; Austria
语种	英语
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202096
作者单位	Institute for Interdisciplinary Mountain Research, Austrian Academy of Sciences, Ict, Technikerstraße, 21a, Innsbruck, 6020, Austria; Enveo It GmbH, Fürstenweg 176, Innsbruck, 6020, Austria
推荐引用方式 GB/T 7714	Hartl L.,Felbauer L.,Schwaizer G.,et al. Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria[J],2020,14(11).
APA	Hartl L.,Felbauer L.,Schwaizer G.,&Fischer A..(2020).Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria.Cryosphere,14(11).
MLA	Hartl L.,et al."Small-scale spatial variability in bare-ice reflectance at Jamtalferner, Austria".Cryosphere 14.11(2020).